i know most gun safes that claim to hold say 20 guns , really need to cut that in half, say 10.
how close are sturdy safes to the actual guns they hold?

Their estimates are accurate but if you do have a lot of ARs or scoped rifles you likely will want the "AR clearance" rack which will hold less but allow more space for receiver / scope height.

I think the estimate of half the rating is pretty close to true.    One thing to consider is the more you try to avoid contact to preserve tte finish, the lower the count.

You might want to consider a Rifle Rods type storage system to squeeze more in there:

Mine is rated at 40 I think but there's no way in hell that's happening unless every rifle was a 10/22 with no scopes.Almost all of my rifles have pistol grips and scopes so 25 is really the max.Don't hold that against Sturdy because every manufacture overrates the capacity.

I've had my Sturdy for 10 years and I'm very happy with it.I thought it was a great value.I've had zero problems.

I would guess that 1/2 capacity is a reasonable bet.  Also, keep in mind the capacities they use are purely for storage.  There is NO WAY you are removing a rifle from the back without first removing every single one in front of it.  So figure how many long term storage rifles do you have v. rifles that you routinely shoot.
I have the "easy access loop" or whatever they call it, and it can still be a pain to get a gun out from the rear.  Can do it, but wouldn't want to with my old/nice wood stock guns as there is a fair bit of bumping.